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/*
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 *
 * Copyright (c) 2002 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */

package org.w3c.dom.xpath;


import org.w3c.dom.Node;
import org.w3c.dom.DOMException;

/**
 * The <code>XPathResult</code> interface represents the result of the evaluation of an XPath 1.0
 * expression within the context of a particular node. Since evaluation of an XPath expression can
 * result in various result types, this object makes it possible to discover and manipulate the type
 * and value of the result. <p>See also the <a href='http://www.w3.org/2002/08/WD-DOM-Level-3-XPath-20020820'>Document
 * Object Model (DOM) Level 3 XPath Specification</a>.
 */
public interface XPathResult {
  // XPathResultType
  /**
   * This code does not represent a specific type. An evaluation of an XPath
   * expression will never produce this type. If this type is requested,
   * then the evaluation returns whatever type naturally results from
   * evaluation of the expression.
   * <br>If the natural result is a node set when <code>ANY_TYPE</code> was
   * requested, then <code>UNORDERED_NODE_ITERATOR_TYPE</code> is always
   * the resulting type. Any other representation of a node set must be
   * explicitly requested.
   */
  public static final short ANY_TYPE = 0;
  /**
   * The result is a number as defined by . Document modification does not
   * invalidate the number, but may mean that reevaluation would not yield
   * the same number.
   */
  public static final short NUMBER_TYPE = 1;
  /**
   * The result is a string as defined by . Document modification does not
   * invalidate the string, but may mean that the string no longer
   * corresponds to the current document.
   */
  public static final short STRING_TYPE = 2;
  /**
   * The result is a boolean as defined by . Document modification does not
   * invalidate the boolean, but may mean that reevaluation would not
   * yield the same boolean.
   */
  public static final short BOOLEAN_TYPE = 3;
  /**
   * The result is a node set as defined by  that will be accessed
   * iteratively, which may not produce nodes in a particular order.
   * Document modification invalidates the iteration.
   * <br>This is the default type returned if the result is a node set and
   * <code>ANY_TYPE</code> is requested.
   */
  public static final short UNORDERED_NODE_ITERATOR_TYPE = 4;
  /**
   * The result is a node set as defined by  that will be accessed
   * iteratively, which will produce document-ordered nodes. Document
   * modification invalidates the iteration.
   */
  public static final short ORDERED_NODE_ITERATOR_TYPE = 5;
  /**
   * The result is a node set as defined by  that will be accessed as a
   * snapshot list of nodes that may not be in a particular order.
   * Document modification does not invalidate the snapshot but may mean
   * that reevaluation would not yield the same snapshot and nodes in the
   * snapshot may have been altered, moved, or removed from the document.
   */
  public static final short UNORDERED_NODE_SNAPSHOT_TYPE = 6;
  /**
   * The result is a node set as defined by  that will be accessed as a
   * snapshot list of nodes that will be in original document order.
   * Document modification does not invalidate the snapshot but may mean
   * that reevaluation would not yield the same snapshot and nodes in the
   * snapshot may have been altered, moved, or removed from the document.
   */
  public static final short ORDERED_NODE_SNAPSHOT_TYPE = 7;
  /**
   * The result is a node set as defined by  and will be accessed as a
   * single node, which may be <code>null</code>if the node set is empty.
   * Document modification does not invalidate the node, but may mean that
   * the result node no longer corresponds to the current document. This
   * is a convenience that permits optimization since the implementation
   * can stop once any node in the in the resulting set has been found.
   * <br>If there are more than one node in the actual result, the single
   * node returned might not be the first in document order.
   */
  public static final short ANY_UNORDERED_NODE_TYPE = 8;
  /**
   * The result is a node set as defined by  and will be accessed as a
   * single node, which may be <code>null</code> if the node set is empty.
   * Document modification does not invalidate the node, but may mean that
   * the result node no longer corresponds to the current document. This
   * is a convenience that permits optimization since the implementation
   * can stop once the first node in document order of the resulting set
   * has been found.
   * <br>If there are more than one node in the actual result, the single
   * node returned will be the first in document order.
   */
  public static final short FIRST_ORDERED_NODE_TYPE = 9;

  /**
   * A code representing the type of this result, as defined by the type
   * constants.
   */
  public short getResultType();

  /**
   * The value of this number result. If the native double type of the DOM
   * binding does not directly support the exact IEEE 754 result of the
   * XPath expression, then it is up to the definition of the binding
   * binding to specify how the XPath number is converted to the native
   * binding number.
   *
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>NUMBER_TYPE</code>.
   */
  public double getNumberValue()
      throws XPathException;

  /**
   * The value of this string result.
   *
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>STRING_TYPE</code>.
   */
  public String getStringValue()
      throws XPathException;

  /**
   * The value of this boolean result.
   *
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>BOOLEAN_TYPE</code>.
   */
  public boolean getBooleanValue()
      throws XPathException;

  /**
   * The value of this single node result, which may be <code>null</code>.
   *
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>ANY_UNORDERED_NODE_TYPE</code> or <code>FIRST_ORDERED_NODE_TYPE</code>.
   */
  public Node getSingleNodeValue()
      throws XPathException;

  /**
   * Signifies that the iterator has become invalid. True if
   * <code>resultType</code> is <code>UNORDERED_NODE_ITERATOR_TYPE</code>
   * or <code>ORDERED_NODE_ITERATOR_TYPE</code> and the document has been
   * modified since this result was returned.
   */
  public boolean getInvalidIteratorState();

  /**
   * The number of nodes in the result snapshot. Valid values for
   * snapshotItem indices are <code>0</code> to
   * <code>snapshotLength-1</code> inclusive.
   *
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
   */
  public int getSnapshotLength()
      throws XPathException;

  /**
   * Iterates and returns the next node from the node set or
   * <code>null</code>if there are no more nodes.
   *
   * @return Returns the next node.
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>UNORDERED_NODE_ITERATOR_TYPE</code> or <code>ORDERED_NODE_ITERATOR_TYPE</code>.
   * @throws DOMException INVALID_STATE_ERR: The document has been mutated since the result was
   * returned.
   */
  public Node iterateNext()
      throws XPathException, DOMException;

  /**
   * Returns the <code>index</code>th item in the snapshot collection. If
   * <code>index</code> is greater than or equal to the number of nodes in
   * the list, this method returns <code>null</code>. Unlike the iterator
   * result, the snapshot does not become invalid, but may not correspond
   * to the current document if it is mutated.
   *
   * @param index Index into the snapshot collection.
   * @return The node at the <code>index</code>th position in the <code>NodeList</code>, or
   * <code>null</code> if that is not a valid index.
   * @throws XPathException TYPE_ERR: raised if <code>resultType</code> is not
   * <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
   */
  public Node snapshotItem(int index)
      throws XPathException;

}
